THERE was a tense stand-off between protesters and gardai today as a machine to tunnel under a picturesque bay was brought in by contractors for Shell.

Scuffles broke out as a huge Garda convoy escorted specialist tunnelling equipment as it travelled from Dublin to the Sruwaddacon Estuary in north Mayo.

Two protesters initially blocked the road on the outskirts of Ballina in the early hours of the morning during a "lock-on", when they chained themselves to a drum filled with cement.

Gardai with specialist cutting equipment cleared the scene, before Shell To Sea campaigner Maura Harrington and another 30 supporters against the controversial Corrib gas project blocked the road closer to Bellacorick bridge near Erris with a van.

"It was very violent and tense for about 30 minutes," said one onlooker.

"The protesters tried to climb on top of the van.

"There were scuffles with guards and people's clothes were torn.

"One woman had her trousers torn off.

"Then about 50 gardai held the crowd back until the convoy passed."

A Garda spokesman said no arrests had been made.

The large tunnel boring machine, which is being used to dig a 4.9km (3-mile) tunnel under Sruwaddacon Bay and inland to the Bellanaboy Gas Processing Terminal, was held up again when more campaigners staged another lock-on about 10km (6 miles) from its final destination.

The equipment, still being transported from Dublin Port on three 40m (131ft) trucks, is being escorted by four Garda vans carrying members of the Public Order Unit, other police vehicles and mini-buses of private security.

Protesters gathered at the port and followed the slow-moving convoy over the last two nights.

Con Coughlan, of the Rossport Solidarity Camp, said the machinery was going to destroy a beautiful estuary and a special area of conservation.

He claimed protesters were "detained illegally" and held in a car park instead of being arrested by gardai.

"It was important we show there is still opposition against this given the amount of resources the State is willing to put behind it," he said.

"There are loads of guards here and we were still able to delay it.

"We are putting those resources behind the richest company in the world when we have no money for the elderly people on hospital trolleys.

"There is something wrong in that world."

Shell E&P Ireland Ltd later confirmed that one of the large trucks carrying part of the tunnel-boring machine had difficulty negotiating a turn on one of the local roads, near the Glenamoy Bridge in Erris.

"The intersection is currently blocked," said a spokesman.

"There are no other vehicles involved. The situation is being assessed and there will be an update when further information becomes available.

"Shell E&P Ireland regrets the inconvenience caused to all public road users as a result of this incident."

However, Terence Conway, of Shell To Sea, said efforts by the firm to bring the 500-ton machine along specially laid roads in the area have been farcical.

"Protesters pulled off three road blockades under the noses of hundreds of gardai," he said.

"In the latest twist, the lorry, which has been on the road for 12 hours so far, failed to make a crucial turn on the last leg of its journey at the Aghoos/Bellinaboy Road due to its size, despite being in a specialist vehicle.

"It continued on to Glenamoy to turn, but has found itself stuck in the process, which included crashing into a local resident's car," he claimed.